Attention is focusing on a wind turbine generation apparatus as an environmentally-friendly power generation facility. The wind turbine generation apparatus generates electric power by rotating a main shaft connected to a blade that receives wind force, speeding up rotation of the main shaft by a gearbox, and then rotating a rotor of a power generator.
The gearbox increases the rotational speed of the main shaft (e.g., 10 to 30 rpm) by a gearbox mechanism to a rotational speed necessary for the power generator (e.g., 1200 to 1800 rpm). This gearbox is an essential part in the wind turbine generation apparatus, and high reliability is required of the gearbox.
One of damage modes of gearbox is gear or bearing abrasion. When gears are worn out, power generation efficiency will deteriorate, and as the degree of abrasion increases, the function as the gearbox may stop. When bearings are worn out, gear backlash will change, which not only degrades transmission efficiency, but also results in damage to the gears. Since a nacelle in which the gearbox is stored is placed at a high position, limits are imposed on in-situ abrasion sensing by an operator.
It is therefore desirable to enable gear or bearing abrasion in the gearbox in the wind turbine generation apparatus to be automatically sensed. Japanese Patent Laying-Open No. 2008-82579 (PTL 1) discloses an abrasion sensing mechanism that senses gear abrasion. This abrasion sensing mechanism is provided with first and second sensors that detect side faces of a gear tooth plane, and gear abrasion is sensed based on the time difference between timing at which a signal of the first sensor changes and timing at which a signal of the second sensor changes when rotating the gear (see PTL 1).
Japanese Patent Laying-Open No. 2005-164314 (PTL 2) discloses sensing bearing abrasion using an ultrasonic sensor, such as an ultrasonic microphone (see PTL 2).